Nursing influences growth rate and overall health of mammals; however, the behavior is difficult to study in wild cetaceans because it occurs below the surface and can thus be misidentified from surface observations. Nursing has been observed in humpback whales on the breeding and calving grounds, but the behavior remains unstudied on the feeding grounds. We instrumented three dependent calves (four total deployments) with combined video and 3D-accelerometer data loggers (CATS) on two United States feeding grounds to document nursing events. Two associated mothers were also tagged to determine if behavior diagnostic of nursing was evident in the mother’s movement. Animal-borne video was manually analyzed and the average duration of successful nursing events was 23 s (±7 sd, n = 11). Nursing occurred at depths between 4.1–64.4 m (along the seafloor) and in close temporal proximity to foraging events by the mothers, but could not be predicted solely by relative positions of mother and calf. When combining all calf deployments, successful nursing was documented eleven times; totaling only 0.3% of 21.0 hours of video. During nursing events, calves had higher overall dynamic body acceleration (ODBA) and increased fluke-stroke rate (FSR) compared to non-nursing segments (Mixed effect models, ODBA: F1,107 = 13.57756, p = 0.0004, FSR: F1,107 = 32.31018, p < 0.0001). In contrast, mothers had lower ODBA and reduced FSR during nursing events compared to non-nursing segments. These data provide the first characterization of accelerometer data of humpback whale nursing confirmed by animal-borne video tags and the first analysis of nursing events on feeding grounds. This is an important step in understanding the energetic consequences of lactation while foraging.

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Bycatch, commonly referred to as entanglement, is a leading source of human-caused mortality of baleen whales. A better understanding of the individuals that survive (or perish from) their entanglement can help reduce the risk of bycatch by informing gear modifications and fisheries management. However, determining survival rates is restricted by the ability to track individuals once they become entangled. Historically, the effort to identify and resight individuals from known entanglement cases was low along the West Coast. The recent increase of entanglements and photo-identification efforts in the California, Oregon, and Washington region provides an opportunity to assess entangled humpback whales’ resighting rates to better understand the effect of entanglements from the individual to the population level. We used photo-ID images of entangled humpback whales between 1982 and 2017 to examine pre- and post-entanglement sighting histories from longitudinal catalogs and life history data (Cascadia Research and Happywhale). We compared the entangled whales (n = 37) against control whales (n = 2,296), selected based on the date and location of the entanglement reports, to evaluate the deviation from the expected mortality rates (or lack of resighting) caused by entanglements and to help inform/support/test National Oceanic and Atmospheric Association’s Serious Injury and Mortality (SI/M) index. Our results suggest that entangled whales were resighted less often than the control groups. Entangled whales with short pre-entanglement sighting histories and without post-entanglement resights did not match other feeding ground populations. Therefore, the higher proportion of entanglements with shorter sighting histories is likely due to their being alive for fewer years, indicating a higher risk of entanglement for younger whales. This indicates that entangled humpback whales may not be as large or strong as mature individuals, and future gear modifications should reflect that possibility. Additionally, the severity of the initial SI/M score aligned well with our resighting rates, though this worsened with the final score assigned. Continued effort to gather and improve data collection about entanglements will help enhance the SI/M determinations. Our findings show the value of photo-identification of entangled whales and how it dramatically increases our understanding of entanglements.

Humpback whales (Megaptera novaeangliae) exhibit maternally driven fidelity to feeding grounds, and yet occasionally occupy new areas. Humpback whale sightings and mortalities in the New York Bight apex (NYBA) have been increasing over the last decade, providing an opportunity to study this phenomenon in an urban habitat. Whales in this area overlap with human activities, including busy shipping traffic leading into the Port of New York and New Jersey. The site fidelity, population composition and demographics of individual whales were analysed to better inform management in this high-risk area. Whale watching and other opportunistic data collections were used to identify 101 individual humpback whales in the NYBA from spring through autumn, 2012–2018. Although mean occurrence was low (2.5 days), mean occupancy was 37.6 days, and 31.3% of whales returned from one year to the next. Individuals compared with other regional and ocean-basin-wide photo-identification catalogues (N = 52) were primarily resighted at other sites along the US East Coast, including the Gulf of Maine feeding ground. Sightings of mother-calf pairs were rare in the NYBA, suggesting that maternally directed fidelity may not be responsible for the presence of young whales in this area. Other factors including shifts in prey species distribution or changes in population structure more broadly should be investigated.